Dysregulation of the circadian rhythm is associated with several disorders of the nervous system including depression, anxiety, schizophrenia and sleep disorders. There is a clear unmet medical need for additional classes of therapeutics to treat these disorders. Anxiety disorders are a serious medical illness affecting approximately 40 million adults in the United States. Benzodiazepenes are the most commonly utilized anxiolytic drugs, but their use is associated with significant side effects including sedation, tolerance and potential for abuse. There are a number of anxiolytic drugs that are now available, but these also are less than optimal. This proposed research is based on our recent discovery that we can modulate the circadian rhythm in vivo with synthetic ligands for a particular nuclear receptor (NR), REV-ERB. REV-ERBa is an NR that has a well characterized role in the regulation of the circadian rhythm. We have found that a REV-ERB agonist that we have designed, SR9011,that has the ability to modulate the circadian rhythm in vivo also displays anxiolytic activity in mice. Interestingly, SR9011 displayed no sedative activity at a dose that exhibited anxiolytic activity. SR9011 is the first REV-ERB ligand with sufficient in vivo exposure to allow evaluation of its effects in animals; however, its pharmacodynamic and pharmcokinetic properties are far from optimal. We hypothesize that optimized synthetic REV-ERB ligands will have utility in treatment of anxiety disorders. We will address this hypothesis by focusing on the following specific aims: 1) Optimize the pharmacodynamic and pharmacokinetic properties of synthetic REV-ERB ligands for use in the CNS, 2) Evaluate the ability of synthetic REV-ERB ligands for their ability to modulate circadian behavior/physiology in vivo, 3) Optimize the anxiolytic activity of REV-ERB agonists in vivo and characterize their sedative activity and potential for abuse. We have now developed a series of very potent and efficacious REV-ERB agonists as well as antagonists that have properties that will allow for evaluation of these compounds in animal models of disease. Thus, our proposed research is highly innovative and has the potential to have high impact since this work may lead to novel drugs for the treatment of anxiety disorders as well as other behavioral disorders. PUBLIC HEALTH RELEVANCE: We discovered that the nuclear receptor REV-ERB is ligand regulated and have characterized both synthetic agonists and antagonists of this receptor. This receptor is a key regulator of the circadian rhythm and dysregulation of the circadian rhythm is associated with several disorders of the nervous system including anxiety disorders. We have discovered that REV-ERB agonists display anxiolytic activity and the goal of this proposal is to develop REV-ERB agonists with optimized pharmacodynamic and pharmacokinetic properties for use as anxiolytic agents.